I wonder, for example, what portion of the mis-behaving 5D3s have s/n lower than RustyTheGeek's replacement camera?

FYI, the replacement 5D3 I received from Beach Camera that performs better has a 4 in the 6th digit and ends in 4736. So my current serial number is xxxxx4xx4736 if that matters or helps anyone. By comparison, the 1st problem 5D3 that I returned had a serial = xxxxx4xx4037.

Not sure if the serial number is relevant to the problem but there it is.

DeckardSolo

My serial is xxxxx4xx5xxx and has the IR focus issue. I've had it for 2 weeks from an authorized seller.In -2EV of light my Rebel 550D was faster than the 5D3 (1/2s vs 1s). In 1EV of light the 5D3 is faster. The test was simple. Fully depress the shutter simultaneously on both bodies to see which shot first (images were in focus).

[The setups were different (5d3+600ex+70-200ii vs 550D+580ex2+24-70v1) but I found in previous tests that combinations of lens and flash did not make a difference to the outcome. Subject was a uniform tiled wall at 8 feet.]

My serial is xxxxx4xx5xxx and has the IR focus issue. I've had it for 2 weeks from an authorized seller.In -2EV of light my Rebel 550D was faster than the 5D3 (1/2s vs 1s). In 1EV of light the 5D3 is faster. The test was simple. Fully depress the shutter simultaneously on both bodies to see which shot first (images were in focus).

[The setups were different (5d3+600ex+70-200ii vs 550D+580ex2+24-70v1) but I found in previous tests that combinations of lens and flash did not make a difference to the outcome. Subject was a uniform tiled wall at 8 feet.]

By themselves, these data do not concern me greatly -- a 1/2 sec penalty for the extraordinary AF accuracy of the 5D3 seems reasonable at first. and thanks for being specific about the light level! But -- with the AF assist beam active, the AF systems are seeing greater than -2EV of light especially since both beams were active at the same time! So to me this is describing a marriage problem between the 5D3 AF system and the assist beam. The fact that the 5D3 focus lock time improves with an increase in light suggests that it is not even looking at (or isn't making very good use of) the assist beam.

now then, take off the flash and force both cameras to focus in -2EV (and other levels of) light. how do they perform?

take both cameras into a closet and close the door ("pitch dark") both cameras should utilize the AF assist beam and should take photos, when tested separately (don't let both assist beams fire simultaneously)

My serial is xxxxx4xx5xxx and has the IR focus issue. I've had it for 2 weeks from an authorized seller.In -2EV of light my Rebel 550D was faster than the 5D3 (1/2s vs 1s). In 1EV of light the 5D3 is faster. The test was simple. Fully depress the shutter simultaneously on both bodies to see which shot first (images were in focus).

[The setups were different (5d3+600ex+70-200ii vs 550D+580ex2+24-70v1) but I found in previous tests that combinations of lens and flash did not make a difference to the outcome. Subject was a uniform tiled wall at 8 feet.]

By themselves, these data do not concern me greatly -- a 1/2 sec penalty for the extraordinary AF accuracy of the 5D3 seems reasonable. and thanks for being specific about the light level! But -- with the AF assist beam active, the AF systems are seeing greater than -2EV of light, especially since both beams were active at the same time! So to me this is describing a marriage problem between the 5D3 AF system and the assist beam. The fact that the 5D3 focus lock time improves with an increase in light suggests that it is not even looking at (or isn't making very good use of) the assist beam.

now then, take off the flash and force both cameras to focus in -2EV (and other levels of) light. how do they perform?

take both cameras into a closet and close the door ("pitch dark") both cameras should utilize the AF assist beam and should take photos, when tested separately (don't let both assist beams fire simultaneously)

With the AF beam on, I can achieve focus in practically no light. Without the AF beam, my camera won't lock focus at all in the same dark room. Are people complaining about the speed of their AF with the AF beam? or the speed of the AF with the AF beam compared to the 5d mk2?

It's the amount of time it takes to lock focus when using the AF beam in low light. Pretty much everyone agrees the focus is spot on when it locks, but it takes considerably longer than it did with the 5DII.

"not sure what the fuss is about" it really is something to worry about when your working with the camera, You have a time limit to deliver photographs and you cant take the shot you need because of this, also there are not allot of golden opportunities to grab a great shot all the time, so you need fast AF when the moment arrives,

this is a problem and Im so hoping the 5D3 gets a load of Love this 2013

I am talking about "working" with the camera... I shoot weddings, kids, candid moments, shows... for money most of the time.

I understand that speed is an issue and you want the camera to be as fast as possible. It just seems there's a bit of an uproar over the issue but the difference in time is less than 1 second (at least for this test). I'm not trying to say there isn't an issue or that we shouldn't have a camera that's at least as fast as the mk2 for the money paid for the mk3. It just sounds like some users need to check their settings and play with the "focus priority/release priority" settings.

@Mike (OP), by chance, did you or can you try running the tests with different settings under the AF2 Menu for both 1st and 2nd shots, as well as the AF3 Menu under one-shot AF release priority?

Just an update on the tests. I've done tons more with different speed lites, targets, etc, most of this has been 6D vs D600 type stuff. Ive even recorded video of how I do the tests so you guys can see and I will post the video here when it is done.

I am not seeing any difference between the 600 or 580 Speedlites. I did look into the auto focus settings on the 5Diii, but as another forum reader pointed out, most of it has to do with AI Servo type shots (which doesnt require a focus lock) to take the shot.

I should probably add a note, as I did on the Canon Forum about why I am going back and forth between the 2 differnent targets at different distances; Target 1 serves mainly to defocus. If im just aiming at target 2 and focusing over and over, its not a good measurement of the cameras ability to get that initial focus.

Another point is that the average focus times for each shot work out to:

5Dii - 1.5s6D - 1.7s5Diii- 2.33s

But this is not what is happening. The focus lock on Target 1 (in good light) is always very quick, almost instantaneous.

Focusing on Target 2 is taking longer than these average times. In fact, most of the time is spent on Target 2.

It is hard to be precise, but I would say the times are closer to:

5Dii - 2.2s6D- 2.5s5Diii - 3 + s

I have a Sekonic 558 Light Meter that seems to be unable to measure the light Im shooting in which would be ideal to know, and am waiting on my new meter - that should help to know exactly at what point it starts to struggle.

Just an update on the tests. I've done tons more with different speed lites, targets, etc, most of this has been 6D vs D600 type stuff. Ive even recorded video of how I do the tests so you guys can see and I will post the video here when it is done.

I am not seeing any difference between the 600 or 580 Speedlites. I did look into the auto focus settings on the 5Diii, but as another forum reader pointed out, most of it has to do with AI Servo type shots (which doesnt require a focus lock) to take the shot.

I should probably add a note, as I did on the Canon Forum about why I am going back and forth between the 2 differnent targets at different distances; Target 1 serves mainly to defocus. If im just aiming at target 2 and focusing over and over, its not a good measurement of the cameras ability to get that initial focus.

Another point is that the average focus times for each shot work out to:

5Dii - 1.5s6D - 1.7s5Diii- 2.33s

But this is not what is happening. The focus lock on Target 1 (in good light) is always very quick, almost instantaneous.

Focusing on Target 2 is taking longer than these average times. In fact, most of the time is spent on Target 2.

It is hard to be precise, but I would say the times are closer to:

5Dii - 2.2s6D- 2.5s5Diii - 3 + s

I have a Sekonic 558 Light Meter that seems to be unable to measure the light Im shooting in which would be ideal to know, and am waiting on my new meter - that should help to know exactly at what point it starts to struggle.

M

Very interesting and very topical stuff Michael. A lot of people are very interested to see what you are doing and really appreciate your efforts.

I think the "two targets" idea is very solid thinking. My only "helpful suggestion" would be to not make one of your 2 focus points be in good light. I think it basically gives the cameras a big boost to their average focus time in bad light. I am sure the 5D3 is super fast in good light, but I think the question is how slow is it in bad light? I would be interested to see the same tests done with two targets, but with both targets being in bad light (none in good light). I think you would see a much more dramatic difference between the cameras if indeed 5d3 struggles in low light AF while 5d2 (or 6D) would not have. THAT would make a real statement.

I use my 5D3 for weddings, receptions etc, and mostly with a 580EXII and find the auto focussing almost instantaneous - and very accurate, with only about 4 out of 600 shots being soft (and those are probably because of me and not the camera), even ln very low-light situations.I've never measured the time it takes to aquire focus in thousanths of a second, but it's plenty quick enough for me.

So it's looking like my thought that now that the 5d has gotten 1D level AF, it gained 1D level AF problems. All of these numbers look like what I would have guessed from my hands on use with this stuff.

Has anyone sent their 5DIII into CPS for repair based on the slow focus lock? Clearly some people don't have the problem (or they just haven't noticed), so it's a case of build quality. If enough people start doing it, perhaps Canon will be forced to at least acknowledge the problem.